Taking over a T-Com landline account

Hi,
this is my situation. I am in Germany until December, so for another 4 and a half months. I have sub-rented a flat. The phone line in the flat is in the name of the main tenant. Now this woman wants me to take over the line ( to get my name on the contract with the telecom ), because she´ll cancel her rent contract all together after I leave and doesn´t want the line for herself. The option in question is a simple T-Net 100 for 15.90 a month.
To sum up, the phone number remains the same, but my name has to be on the contract.
How much will the telecom charge me for that change?
Do not shock me, please.

I can't comment on the cost, but I would advise you to check the cancellation period for when you leave in a few months. Actually I think Telekom is one of the few German companies who don't make you stick to huge contract and cancellation periods, but it would be wise to check.

According to my neighbour who works for DT-com, you can't just take over a land line like that. We're in a similar situation with the house we just bought. We could theoretically just take over the existing land line number but it isn't allowed. The original contract must be cancelled by the contract holder, and we get a new number and new contract under our name.

Would it not be possible to change the existing contract to a joint contract, adding you onto it.
Then in 4 months just make it a single person contract, leaving her off it??

Unless you are a close relative of the current line owner you cannot "take over" an existing line and number. Main reason for this is a data protection issue. They must cancel their line and you must start a new contract and get a new number. Cost for this is €59.95 connection charge for the phone line plus €99.95 connection charge if you want a DSL service as well. A new, standard T-Net-Call-Plus line (the cheapest analogue line) has a minimum contract period of 1 month, thereafter 6 days notice of cancellation is required. All other T-Net connections have minimum 12 month contracts. On certain package combinations, and certainly with other providers you may be able to avoid the connection charges, but in all cases minimum contract would then be 12 months, sometimes 24.
You only alternative solution is to ask the current line "owner" to give Telekom your bank details for the monthly invoice deductions. That way they keep the line and responsibility for it, but you pay for it directly. No additional cost for this solution, but you do need to be sure your name gets removed from the payment system when you eventually leave the apartment